/* 
* Modified from the following linenoise source.
*
* Copyright (c) 2014 Texas Instruments Inc.
*
* ---------------------------------------------------------------------
* linenoise.c -- guerrilla line editing library against the idea that a
* line editing lib needs to be 20,000 lines of C code.
*
* You can find the latest source code at:
*
*   http://github.com/msteveb/linenoise
*   (forked from http://github.com/antirez/linenoise)
*
* Does a number of crazy assumptions that happen to be true in 99.9999% of
* the 2010 UNIX computers around.
*
* ------------------------------------------------------------------------
*
* Copyright (c) 2010, Salvatore Sanfilippo <antirez at gmail dot com>
* Copyright (c) 2010, Pieter Noordhuis <pcnoordhuis at gmail dot com>
* Copyright (c) 2011, Steve Bennett <steveb at workware dot net dot au>
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
*  *  Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*
*  *  Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in the
*     documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* ------------------------------------------------------------------------
*
* References:
* - http://invisible-island.net/xterm/ctlseqs/ctlseqs.html
* - http://www.3waylabs.com/nw/WWW/products/wizcon/vt220.html
*
* Bloat:
* - Completion?
*
* Unix/termios
* ------------
* List of escape sequences used by this program, we do everything just
* a few sequences. In order to be so cheap we may have some
* flickering effect with some slow terminal, but the lesser sequences
* the more compatible.
*
* EL (Erase Line)
*    Sequence: ESC [ n K
*    Effect: if n is 0 or missing, clear from cursor to end of line
*    Effect: if n is 1, clear from beginning of line to cursor
*    Effect: if n is 2, clear entire line
*
* CUF (CUrsor Forward)
*    Sequence: ESC [ n C
*    Effect: moves cursor forward of n chars
*
* CR (Carriage Return)
*    Sequence: \r
*    Effect: moves cursor to column 1
*
* The following are used to clear the screen: ESC [ H ESC [ 2 J
* This is actually composed of two sequences:
*
* cursorhome
*    Sequence: ESC [ H
*    Effect: moves the cursor to upper left corner
*
* ED2 (Clear entire screen)
*    Sequence: ESC [ 2 J
*    Effect: clear the whole screen
*
* == For highlighting control characters, we also use the following two ==
* SO (enter StandOut)
*    Sequence: ESC [ 7 m
*    Effect: Uses some standout mode such as reverse video
*
* SE (Standout End)
*    Sequence: ESC [ 0 m
*    Effect: Exit standout mode
*
* == Only used if TIOCGWINSZ fails ==
* DSR/CPR (Report cursor position)
*    Sequence: ESC [ 6 n
*    Effect: reports current cursor position as ESC [ NNN ; MMM R
*
* win32/console
* -------------
* If __MINGW32__ is defined, the win32 console API is used.
* This could probably be made to work for the msvc compiler too.
* This support based in part on work by Jon Griffiths.
*/

#ifdef _WIN32 /* Windows platform, either MinGW or Visual Studio (MSVC) */
#include <windows.h>
#include <fcntl.h>
#define USE_WINCONSOLE
#ifdef __MINGW32__
#define HAVE_UNISTD_H
#else
/* Microsoft headers don't like old POSIX names */
#define strdup _strdup
#if defined(_MSC_VER) && (_MSC_VER < 1900 )
#define snprintf _snprintf
#endif
#endif
#else
#include <termios.h>
#include <sys/ioctl.h>
#include <sys/poll.h>
#define USE_TERMIOS
#define HAVE_UNISTD_H
#endif

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <stdlib.h>
#include <stdarg.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>

#include "LineNoise.h"
#include "LineNoiseUTF8.h"

#define LINENOISE_DEFAULT_HISTORY_MAX_LEN 100
#define LINENOISE_MAX_LINE 4096

#define ctrl(C) ((C) - '@')

namespace LineNoise
{

/* Use -ve numbers here to co-exist with normal unicode chars */
enum {
  SPECIAL_NONE,
  SPECIAL_UP = -20,
  SPECIAL_DOWN = -21,
  SPECIAL_LEFT = -22,
  SPECIAL_RIGHT = -23,
  SPECIAL_DELETE = -24,
  SPECIAL_HOME = -25,
  SPECIAL_END = -26,
  SPECIAL_INSERT = -27,
  SPECIAL_PAGE_UP = -28,
  SPECIAL_PAGE_DOWN = -29
};

static int history_max_len = LINENOISE_DEFAULT_HISTORY_MAX_LEN;
static int history_len = 0;
static char **history = NULL;

/* Structure to contain the status of the current (being edited) line */
struct current {
  char *buf;  /* Current buffer. Always null terminated */
  int bufmax; /* Size of the buffer, including space for the null termination */
  int len;    /* Number of bytes in 'buf' */
  int chars;  /* Number of chars in 'buf' (utf-8 chars) */
  int pos;    /* Cursor position, measured in chars */
  int cols;   /* Size of the window, in chars */
  const char *prompt;
  char *capture; /* Allocated capture buffer, or NULL for none. Always null terminated */
#if defined(USE_TERMIOS)
  int fd;     /* Terminal fd */
#elif defined(USE_WINCONSOLE)
  HANDLE outh; /* Console output handle */
  HANDLE inh; /* Console input handle */
  int rows;   /* Screen rows */
  int x;      /* Current column during output */
  int y;      /* Current row */
#endif
};

static int fd_read(struct current *current);
static int getWindowSize(struct current *current);

void linenoiseHistoryFree(void) {
  if (history) {
    int j;

    for (j = 0; j < history_len; j++)
      free(history[j]);
    free(history);
    history = NULL;
    history_len = 0;
  }
}

#if defined(USE_TERMIOS)
static void linenoiseAtExit(void);
static struct termios raw_termios, orig_termios; /* in order to restore at exit */
static int rawmode = 0; /* for atexit() function to check if restore is needed*/
static int atexit_registered = 0; /* register atexit just 1 time */

static const char *unsupported_term[] = { "dumb", "cons25", NULL };

static int isUnsupportedTerm(void) {
  char *term = getenv("TERM");

  if (term) {
    int j;
    for (j = 0; unsupported_term[j]; j++) {
      if (strcmp(term, unsupported_term[j]) == 0) {
        return 1;
      }
    }
  }
  return 0;
}

static int enableRawMode(struct current *current) {
  current->fd = STDIN_FILENO;
  current->cols = 0;

  if (!isatty(current->fd) || isUnsupportedTerm() ||
    tcgetattr(current->fd, &orig_termios) == -1) {
  fatal:
    errno = ENOTTY;
    return -1;
  }

  if (!atexit_registered) {
    atexit(linenoiseAtExit);
    atexit_registered = 1;
  }

  raw_termios = orig_termios;  /* modify the original mode */
  /* input modes: no break, no CR to NL, no parity check, no strip char,
  * no start/stop output control. */
  raw_termios.c_oflag |= (OCRNL | ONLCR); //HLP
  raw_termios.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON); //HLP
  /* output modes - disable post processing */
  //raw.c_oflag &= ~(OPOST); //HLP
  /* control modes - set 8 bit chars */
  raw_termios.c_cflag |= (CS8);
  /* local modes - choing off, canonical off, no extended functions,
  * no signal chars (^Z,^C) */
  raw_termios.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
  /* control chars - set return condition: min number of bytes and timer.
  * We want read to return every single byte, without timeout. */
  raw_termios.c_cc[VMIN] = 1; raw_termios.c_cc[VTIME] = 0; /* 1 byte, no timer */

  /* put terminal in raw mode after flushing */
  if (tcsetattr(current->fd, TCSADRAIN, &raw_termios) < 0) {
    goto fatal;
  }
  rawmode = 1;
  return 0;
}

// HLP Added enable/disableRawModeOutput()
static int enableRawModeOutput(int fd) {
  raw_termios.c_oflag &= ~(OPOST);
  /* put terminal in raw mode after flushing */
  if (tcsetattr(fd, TCSADRAIN, &raw_termios) < 0) {
    errno = ENOTTY;
    return -1;
  }
  return 0;
}

static int disableRawModeOutput(int fd) {
  raw_termios.c_oflag |= (OPOST);
  /* put terminal in raw mode after flushing */
  if (tcsetattr(fd, TCSADRAIN, &raw_termios) < 0) {
    errno = ENOTTY;
    return -1;
  }
  return 0;
}

static void disableRawMode(struct current *current) {
  /* Don't even check the return value as it's too late. */
  if (rawmode && tcsetattr(current->fd, TCSADRAIN, &orig_termios) != -1)
    rawmode = 0;
}

/* At exit we'll try to fix the terminal to the initial conditions. */
static void linenoiseAtExit(void) {
  if (rawmode) {
    tcsetattr(STDIN_FILENO, TCSADRAIN, &orig_termios);
  }
  linenoiseHistoryFree();
}

/* gcc/glibc insists that we care about the return code of write!
* Clarification: This means that a void-cast like "(void) (EXPR)"
* does not work.
*/
#define IGNORE_RC(EXPR) if (EXPR) {}

/* This is fdprintf() on some systems, but use a different
* name to avoid conflicts
*/
static void fd_printf(int fd, const char *format, ...)
{
  va_list args;
  char buf[64];
  int n;

  enableRawModeOutput(fd);
  
  va_start(args, format);
  n = vsnprintf(buf, sizeof(buf), format, args);
  va_end(args);
  IGNORE_RC(write(fd, buf, n));
  
  disableRawModeOutput(fd);
}

static void clearScreen(struct current *current)
{
  fd_printf(current->fd, "\x1b[H\x1b[2J");
}

static void cursorToLeft(struct current *current)
{
  fd_printf(current->fd, "\r");
}

static int outputChars(struct current *current, const char *buf, int len)
{
  return write(current->fd, buf, len);
}

static void outputControlChar(struct current *current, char ch)
{
  fd_printf(current->fd, "\x1b[7m^%c\x1b[0m", ch);
}

static void eraseEol(struct current *current)
{
  fd_printf(current->fd, "\x1b[0K");
}

static void setCursorPos(struct current *current, int x)
{
  fd_printf(current->fd, "\r\x1b[%dC", x);
}

/**
* Reads a char from 'fd', waiting at most 'timeout' milliseconds.
*
* A timeout of -1 means to wait forever.
*
* Returns -1 if no char is received within the time or an error occurs.
*/
static int fd_read_char(int fd, int timeout)
{
  struct pollfd p;
  unsigned char c;

  p.fd = fd;
  p.events = POLLIN;

  if (poll(&p, 1, timeout) == 0) {
    /* timeout */
    return -1;
  }
  if (read(fd, &c, 1) != 1) {
    return -1;
  }
  return c;
}

/**
* Reads a complete utf-8 character
* and returns the unicode value, or -1 on error.
*/
static int fd_read(struct current *current)
{
#ifdef USE_UTF8
  char buf[4];
  int n;
  int i;
  int c;

  if (read(current->fd, &buf[0], 1) != 1) {
    return -1;
  }
  n = utf8_charlen(buf[0]);
  if (n < 1 || n > 3) {
    return -1;
  }
  for (i = 1; i < n; i++) {
    if (read(current->fd, &buf[i], 1) != 1) {
      return -1;
    }
  }
  buf[n] = 0;
  /* decode and return the character */
  utf8_tounicode(buf, &c);
  return c;
#else
  return fd_read_char(current->fd, -1);
#endif
}

static int countColorControlChars(const char* prompt)
{
  /* ANSI color control sequences have the form:
  * "\x1b" "[" [0-9;]* "m"
  * We parse them with a simple state machine.
  */

  enum {
    search_esc,
    expect_bracket,
    expect_trail
  } state = search_esc;
  int len = 0, found = 0;
  char ch;

  /* XXX: Strictly we should be checking utf8 chars rather than
  *      bytes in case of the extremely unlikely scenario where
  *      an ANSI sequence is part of a utf8 sequence.
  */
  while ((ch = *prompt++) != 0) {
    switch (state) {
    case search_esc:
      if (ch == '\x1b') {
        state = expect_bracket;
      }
      break;
    case expect_bracket:
      if (ch == '[') {
        state = expect_trail;
        /* 3 for "\e[ ... m" */
        len = 3;
        break;
      }
      state = search_esc;
      break;
    case expect_trail:
      if ((ch == ';') || ((ch >= '0' && ch <= '9'))) {
        /* 0-9, or semicolon */
        len++;
        break;
      }
      if (ch == 'm') {
        found += len;
      }
      state = search_esc;
      break;
    }
  }

  return found;
}

/**
* Stores the current cursor column in '*cols'.
* Returns 1 if OK, or 0 if failed to determine cursor pos.
*/
static int queryCursor(int fd, int* cols)
{
  /* control sequence - report cursor location */
  fd_printf(fd, "\x1b[6n");

  /* Parse the response: ESC [ rows ; cols R */
  if (fd_read_char(fd, 100) == 0x1b &&
    fd_read_char(fd, 100) == '[') {

    int n = 0;
    while (1) {
      int ch = fd_read_char(fd, 100);
      if (ch == ';') {
        /* Ignore rows */
        n = 0;
      }
      else if (ch == 'R') {
        /* Got cols */
        if (n != 0 && n < 1000) {
          *cols = n;
        }
        break;
      }
      else if (ch >= 0 && ch <= '9') {
        n = n * 10 + ch - '0';
      }
      else {
        break;
      }
    }
    return 1;
  }

  return 0;
}

/**
* Updates current->cols with the current window size (width)
*/
static int getWindowSize(struct current *current)
{
  struct winsize ws;

  if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == 0 && ws.ws_col != 0) {
    current->cols = ws.ws_col;
    return 0;
  }

  /* Failed to query the window size. Perhaps we are on a serial terminal.
  * Try to query the width by sending the cursor as far to the right
  * and reading back the cursor position.
  * Note that this is only done once per call to linenoise rather than
  * every time the line is refreshed for efficiency reasons.
  *
  * In more detail, we:
  * (a) request current cursor position,
  * (b) move cursor far right,
  * (c) request cursor position again,
  * (d) at last move back to the old position.
  * This gives us the width without messing with the externally
  * visible cursor position.
  */

  if (current->cols == 0) {
    int here;

    current->cols = 80;

    /* (a) */
    if (queryCursor(current->fd, &here)) {
      /* (b) */
      fd_printf(current->fd, "\x1b[999C");

      /* (c). Note: If (a) succeeded, then (c) should as well.
      * For paranoia we still check and have a fallback action
      * for (d) in case of failure..
      */
      if (!queryCursor(current->fd, &current->cols)) {
        /* (d') Unable to get accurate position data, reset
        * the cursor to the far left. While this may not
        * restore the exact original position it should not
        * be too bad.
        */
        fd_printf(current->fd, "\r");
      }
      else {
        /* (d) Reset the cursor back to the original location. */
        if (current->cols > here) {
          fd_printf(current->fd, "\x1b[%dD", current->cols - here);
        }
      }
    } /* 1st query failed, doing nothing => default 80 */
  }

  return 0;
}

/**
* If escape (27) was received, reads subsequent
* chars to determine if this is a known special key.
*
* Returns SPECIAL_NONE if unrecognised, or -1 if EOF.
*
* If no additional char is received within a short time,
* 27 is returned.
*/
static int check_special(int fd)
{
  int c = fd_read_char(fd, 50);
  int c2;

  if (c < 0) {
    return 27;
  }

  c2 = fd_read_char(fd, 50);
  if (c2 < 0) {
    return c2;
  }
  if (c == '[' || c == 'O') {
    /* Potential arrow key */
    switch (c2) {
    case 'A':
      return SPECIAL_UP;
    case 'B':
      return SPECIAL_DOWN;
    case 'C':
      return SPECIAL_RIGHT;
    case 'D':
      return SPECIAL_LEFT;
    case 'F':
      return SPECIAL_END;
    case 'H':
      return SPECIAL_HOME;
    }
  }
  if (c == '[' && c2 >= '1' && c2 <= '8') {
    /* extended escape */
    c = fd_read_char(fd, 50);
    if (c == '~') {
      switch (c2) {
      case '2':
        return SPECIAL_INSERT;
      case '3':
        return SPECIAL_DELETE;
      case '5':
        return SPECIAL_PAGE_UP;
      case '6':
        return SPECIAL_PAGE_DOWN;
      case '7':
        return SPECIAL_HOME;
      case '8':
        return SPECIAL_END;
      }
    }
    while (c != -1 && c != '~') {
      /* .e.g \e[12~ or '\e[11;2~   discard the complete sequence */
      c = fd_read_char(fd, 50);
    }
  }

  return SPECIAL_NONE;
}
#elif defined(USE_WINCONSOLE)

static DWORD orig_consolemode = 0;

static int enableRawMode(struct current *current) {
  DWORD n;
  INPUT_RECORD irec;

  current->outh = GetStdHandle(STD_OUTPUT_HANDLE);
  current->inh = GetStdHandle(STD_INPUT_HANDLE);

  if (!PeekConsoleInput(current->inh, &irec, 1, &n)) {
    return -1;
  }
  if (getWindowSize(current) != 0) {
    return -1;
  }
  if (GetConsoleMode(current->inh, &orig_consolemode)) {
    SetConsoleMode(current->inh, ENABLE_PROCESSED_INPUT);
  }
  return 0;
}

static void disableRawMode(struct current *current)
{
  SetConsoleMode(current->inh, orig_consolemode);
}

static void clearScreen(struct current *current)
{
  COORD topleft = { 0, 0 };
  DWORD n;

  FillConsoleOutputCharacter(current->outh, ' ',
    current->cols * current->rows, topleft, &n);
  FillConsoleOutputAttribute(current->outh,
    FOREGROUND_RED | FOREGROUND_BLUE | FOREGROUND_GREEN,
    current->cols * current->rows, topleft, &n);
  SetConsoleCursorPosition(current->outh, topleft);
}

static void cursorToLeft(struct current *current)
{
  COORD pos = { 0, (SHORT)current->y };
  DWORD n;

  FillConsoleOutputAttribute(current->outh,
    FOREGROUND_RED | FOREGROUND_BLUE | FOREGROUND_GREEN, current->cols, pos, &n);
  current->x = 0;
}

static int outputChars(struct current *current, const char *buf, int len)
{
  COORD pos = { (SHORT)current->x, (SHORT)current->y };
  DWORD n;

  WriteConsoleOutputCharacter(current->outh, buf, len, pos, &n);
  current->x += len;
  return 0;
}

static void outputControlChar(struct current *current, char ch)
{
  COORD pos = { (SHORT)current->x, (SHORT)current->y };
  DWORD n;

  FillConsoleOutputAttribute(current->outh, BACKGROUND_INTENSITY, 2, pos, &n);
  outputChars(current, "^", 1);
  outputChars(current, &ch, 1);
}

static void eraseEol(struct current *current)
{
  COORD pos = { (SHORT)current->x, (SHORT)current->y };
  DWORD n;

  FillConsoleOutputCharacter(current->outh, ' ', current->cols - current->x, pos, &n);
}

static void setCursorPos(struct current *current, int x)
{
  COORD pos = { (SHORT)x, (SHORT)current->y };

  SetConsoleCursorPosition(current->outh, pos);
  current->x = x;
}

static int fd_read(struct current *current)
{
  while (1) {
    INPUT_RECORD irec;
    DWORD n;
    if (WaitForSingleObject(current->inh, INFINITE) != WAIT_OBJECT_0) {
      break;
    }
    if (!ReadConsoleInput(current->inh, &irec, 1, &n)) {
      break;
    }
    if (irec.EventType == KEY_EVENT && irec.Event.KeyEvent.bKeyDown) {
      KEY_EVENT_RECORD *k = &irec.Event.KeyEvent;
      if (k->dwControlKeyState & ENHANCED_KEY) {
        switch (k->wVirtualKeyCode) {
        case VK_LEFT:
          return SPECIAL_LEFT;
        case VK_RIGHT:
          return SPECIAL_RIGHT;
        case VK_UP:
          return SPECIAL_UP;
        case VK_DOWN:
          return SPECIAL_DOWN;
        case VK_INSERT:
          return SPECIAL_INSERT;
        case VK_DELETE:
          return SPECIAL_DELETE;
        case VK_HOME:
          return SPECIAL_HOME;
        case VK_END:
          return SPECIAL_END;
        case VK_PRIOR:
          return SPECIAL_PAGE_UP;
        case VK_NEXT:
          return SPECIAL_PAGE_DOWN;
        }
      }
      /* Note that control characters are already translated in AsciiChar */
      else if (k->wVirtualKeyCode == VK_CONTROL)
        continue;
      else {
#ifdef USE_UTF8
        return k->uChar.UnicodeChar;
#else
        return k->uChar.AsciiChar;
#endif
      }
    }
  }
  return -1;
}

static int countColorControlChars(const char* prompt)
{
  /* For windows we assume that there are no embedded ansi color
  * control sequences.
  */
  return 0;
}

static int getWindowSize(struct current *current)
{
  CONSOLE_SCREEN_BUFFER_INFO info;
  if (!GetConsoleScreenBufferInfo(current->outh, &info)) {
    return -1;
  }
  current->cols = info.dwSize.X;
  current->rows = info.dwSize.Y;
  if (current->cols <= 0 || current->rows <= 0) {
    current->cols = 80;
    return -1;
  }
  current->y = info.dwCursorPosition.Y;
  current->x = info.dwCursorPosition.X;
  return 0;
}
#endif

static int utf8_getchars(char *buf, int c)
{
#ifdef USE_UTF8
  return utf8_fromunicode(buf, c);
#else
  *buf = c;
  return 1;
#endif
}

/**
* Returns the unicode character at the given offset,
* or -1 if none.
*/
static int get_char(struct current *current, int pos)
{
  if (pos >= 0 && pos < current->chars) {
    int c;
    int i = utf8_index(current->buf, pos);
    (void)utf8_tounicode(current->buf + i, &c);
    return c;
  }
  return -1;
}

static void refreshLine(const char *prompt, struct current *current)
{
  int plen;
  int pchars;
  int backup = 0;
  int i;
  const char *buf = current->buf;
  int chars = current->chars;
  int pos = current->pos;
  int b;
  int ch;
  int n;

  /* Should intercept SIGWINCH. For now, just get the size every time */
  getWindowSize(current);

  plen = strlen(prompt);
  pchars = utf8_strlen(prompt, plen);

  /* Scan the prompt for embedded ansi color control sequences and
  * discount them as characters/columns.
  */
  pchars -= countColorControlChars(prompt);

  /* Account for a line which is too long to fit in the window.
  * Note that control chars require an extra column
  */

  /* How many cols are required to the left of 'pos'?
  * The prompt, plus one extra for each control char
  */
  n = pchars + utf8_strlen(buf, current->len);
  b = 0;
  for (i = 0; i < pos; i++) {
    b += utf8_tounicode(buf + b, &ch);
    if (ch < ' ') {
      n++;
    }
  }

  /* If too many are needed, strip chars off the front of 'buf'
  * until it fits. Note that if the current char is a control character,
  * we need one extra col.
  */
  if (current->pos < current->chars && get_char(current, current->pos) < ' ') {
    n++;
  }

  while (n >= current->cols && pos > 0) {
    b = utf8_tounicode(buf, &ch);
    if (ch < ' ') {
      n--;
    }
    n--;
    buf += b;
    pos--;
    chars--;
  }

  /* Cursor to left edge, then the prompt */
  cursorToLeft(current);
  outputChars(current, prompt, plen);

  /* Now the current buffer content */

  /* Need special handling for control characters.
  * If we hit 'cols', stop.
  */
  b = 0; /* unwritted bytes */
  n = 0; /* How many control chars were written */
  for (i = 0; i < chars; i++) {
    int ch;
    int w = utf8_tounicode(buf + b, &ch);
    if (ch < ' ') {
      n++;
    }
    if (pchars + i + n >= current->cols) {
      break;
    }
    if (ch < ' ') {
      /* A control character, so write the buffer so far */
      outputChars(current, buf, b);
      buf += b + w;
      b = 0;
      outputControlChar(current, ch + '@');
      if (i < pos) {
        backup++;
      }
    }
    else {
      b += w;
    }
  }
  outputChars(current, buf, b);

  /* Erase to right, move cursor to original position */
  eraseEol(current);
  setCursorPos(current, pos + pchars + backup);
}

static void set_current(struct current *current, const char *str)
{
  strncpy(current->buf, str, current->bufmax);
  current->buf[current->bufmax - 1] = 0;
  current->len = strlen(current->buf);
  current->pos = current->chars = utf8_strlen(current->buf, current->len);
}

static int has_room(struct current *current, int bytes)
{
  return current->len + bytes < current->bufmax - 1;
}

/**
* Removes the char at 'pos'.
*
* Returns 1 if the line needs to be refreshed, 2 if not
* and 0 if nothing was removed
*/
static int remove_char(struct current *current, int pos)
{
  if (pos >= 0 && pos < current->chars) {
    int p1, p2;
    int ret = 1;
    p1 = utf8_index(current->buf, pos);
    p2 = p1 + utf8_index(current->buf + p1, 1);

#ifdef USE_TERMIOS
    /* optimise remove char in the case of removing the last char */
    if (current->pos == pos + 1 && current->pos == current->chars) {
      if (current->buf[pos] >= ' ' && utf8_strlen(current->prompt, -1) + utf8_strlen(current->buf, current->len) < current->cols - 1) {
        ret = 2;
        fd_printf(current->fd, "\b \b");
      }
    }
#endif

    /* Move the null char too */
    memmove(current->buf + p1, current->buf + p2, current->len - p2 + 1);
    current->len -= (p2 - p1);
    current->chars--;

    if (current->pos > pos) {
      current->pos--;
    }
    return ret;
  }
  return 0;
}

/**
* Insert 'ch' at position 'pos'
*
* Returns 1 if the line needs to be refreshed, 2 if not
* and 0 if nothing was inserted (no room)
*/
static int insert_char(struct current *current, int pos, int ch)
{
  char buf[3];
  int n = utf8_getchars(buf, ch);

  if (has_room(current, n) && pos >= 0 && pos <= current->chars) {
    int p1, p2;
    int ret = 1;
    p1 = utf8_index(current->buf, pos);
    p2 = p1 + n;

#ifdef USE_TERMIOS
    /* optimise the case where adding a single char to the end and no scrolling is needed */
    if (current->pos == pos && current->chars == pos) {
      if (ch >= ' ' && utf8_strlen(current->prompt, -1) + utf8_strlen(current->buf, current->len) < current->cols - 1) {
        IGNORE_RC(write(current->fd, buf, n));
        ret = 2;
      }
    }
#endif

    memmove(current->buf + p2, current->buf + p1, current->len - p1);
    memcpy(current->buf + p1, buf, n);
    current->len += n;

    current->chars++;
    if (current->pos >= pos) {
      current->pos++;
    }
    return ret;
  }
  return 0;
}

/**
* Captures up to 'n' characters starting at 'pos' for the cut buffer.
*
* This replaces any existing characters in the cut buffer.
*/
static void capture_chars(struct current *current, int pos, int n)
{
  if (pos >= 0 && (pos + n - 1) < current->chars) {
    int p1 = utf8_index(current->buf, pos);
    int nbytes = utf8_index(current->buf + p1, n);

    if (nbytes) {
      free(current->capture);
      /* Include space for the null terminator */
      current->capture = (char *)malloc(nbytes + 1);
      memcpy(current->capture, current->buf + p1, nbytes);
      current->capture[nbytes] = '\0';
    }
  }
}

/**
* Removes up to 'n' characters at cursor position 'pos'.
*
* Returns 0 if no chars were removed or non-zero otherwise.
*/
static int remove_chars(struct current *current, int pos, int n)
{
  int removed = 0;

  /* First save any chars which will be removed */
  capture_chars(current, pos, n);

  while (n-- && remove_char(current, pos)) {
    removed++;
  }
  return removed;
}
/**
* Inserts the characters (string) 'chars' at the cursor position 'pos'.
*
* Returns 0 if no chars were inserted or non-zero otherwise.
*/
static int insert_chars(struct current *current, int pos, const char *chars)
{
  int inserted = 0;

  while (*chars) {
    int ch;
    int n = utf8_tounicode(chars, &ch);
    if (insert_char(current, pos, ch) == 0) {
      break;
    }
    inserted++;
    pos++;
    chars += n;
  }
  return inserted;
}

#ifndef NO_COMPLETION
static LinenoiseCompletionCallback completionCallback = nullptr;

static void beep() {
#ifdef USE_TERMIOS
  fprintf(stderr, "\x7");
  fflush(stderr);
#endif
}

static void freeCompletions(linenoiseCompletions *lc) {
  size_t i;
  for (i = 0; i < lc->len; i++)
    free(lc->cvec[i]);
  free(lc->cvec);
}

static int completeLine(struct current *current) {
  linenoiseCompletions lc = { 0, NULL };
  int c = 0;

  completionCallback(current->buf, &lc);
  if (lc.len == 0) {
    beep();
  }
  else {
    size_t stop = 0, i = 0;

    while (!stop) {
      /* Show completion or original buffer */
      if (i < lc.len) {
        struct current tmp = *current;
        tmp.buf = lc.cvec[i];
        tmp.pos = tmp.len = strlen(tmp.buf);
        tmp.chars = utf8_strlen(tmp.buf, tmp.len);
        refreshLine(current->prompt, &tmp);
      }
      else {
        refreshLine(current->prompt, current);
      }

      c = fd_read(current);
      if (c == -1) {
        break;
      }

      switch (c) {
      case '\t': /* tab */
        i = (i + 1) % (lc.len + 1);
        if (i == lc.len) beep();
        break;
      case 27: /* escape */
        /* Re-show original buffer */
        if (i < lc.len) {
          refreshLine(current->prompt, current);
        }
        stop = 1;
        break;
      default:
        /* Update buffer and return */
        if (i < lc.len) {
          set_current(current, lc.cvec[i]);
        }
        stop = 1;
        break;
      }
    }
  }

  freeCompletions(&lc);
  return c; /* Return last read character */
}

/* Register a callback function to be called for tab-completion.
Returns the prior callback so that the caller may (if needed)
restore it when done. */
LinenoiseCompletionCallback linenoiseSetCompletionCallback(LinenoiseCompletionCallback fn) {
  completionCallback = fn;
  return fn;
}


void linenoiseAddCompletion(linenoiseCompletions *lc, const char *str) {
  lc->cvec = (char **)realloc(lc->cvec, sizeof(char*)*(lc->len + 1));
  lc->cvec[lc->len++] = strdup(str);
}

#endif

static int linenoiseEdit(struct current *current) {
  int history_index = 0;

  /* The latest history entry is always our current buffer, that
  * initially is just an empty string. */
  linenoiseHistoryAdd("");

  set_current(current, "");
  refreshLine(current->prompt, current);

  while (1) {
    int dir = -1;
    int c = fd_read(current);

#ifndef NO_COMPLETION
    /* Only autocomplete when the callback is set. It returns < 0 when
    * there was an error reading from fd. Otherwise it will return the
    * character that should be handled next. */
    if (c == '\t' && current->pos == current->chars && completionCallback != NULL) {
      c = completeLine(current);
      /* Return on errors */
      if (c < 0) return current->len;
      /* Read next character when 0 */
      if (c == 0) continue;
    }
#endif

  process_char:
    if (c == -1) return current->len;
#ifdef USE_TERMIOS
    if (c == 27) {   /* escape sequence */
      c = check_special(current->fd);
    }
#endif
    switch (c) {
    case '\r':    /* enter */
      history_len--;
      free(history[history_len]);
      return current->len;
    case ctrl('C'):     /* ctrl-c */
      errno = EAGAIN;
      return -1;
    case 127:   /* backspace */
    case ctrl('H'):
      if (remove_char(current, current->pos - 1) == 1) {
        refreshLine(current->prompt, current);
      }
      break;
    case ctrl('D'):     /* ctrl-d */
      if (current->len == 0) {
        /* Empty line, so EOF */
        history_len--;
        free(history[history_len]);
        return -1;
      }
      /* Otherwise fall through to delete char to right of cursor */
    case SPECIAL_DELETE:
      if (remove_char(current, current->pos) == 1) {
        refreshLine(current->prompt, current);
      }
      break;
    case SPECIAL_INSERT:
      /* Ignore. Expansion Hook.
      * Future possibility: Toggle Insert/Overwrite Modes
      */
      break;
    case ctrl('W'):    /* ctrl-w, delete word at left. save deleted chars */
      /* eat any spaces on the left */
    {
      int pos = current->pos;
      while (pos > 0 && get_char(current, pos - 1) == ' ') {
        pos--;
      }

      /* now eat any non-spaces on the left */
      while (pos > 0 && get_char(current, pos - 1) != ' ') {
        pos--;
      }

      if (remove_chars(current, pos, current->pos - pos)) {
        refreshLine(current->prompt, current);
      }
    }
    break;
    case ctrl('R'):    /* ctrl-r */
    {
      /* Display the reverse-i-search prompt and process chars */
      char rbuf[50];
      char rprompt[80];
      int rchars = 0;
      int rlen = 0;
      int searchpos = history_len - 1;

      rbuf[0] = 0;
      while (1) {
        int n = 0;
        const char *p = NULL;
        int skipsame = 0;
        int searchdir = -1;

        snprintf(rprompt, sizeof(rprompt), "(reverse-i-search)'%s': ", rbuf);
        refreshLine(rprompt, current);
        c = fd_read(current);
        if (c == ctrl('H') || c == 127) {
          if (rchars) {
            int p = utf8_index(rbuf, --rchars);
            rbuf[p] = 0;
            rlen = strlen(rbuf);
          }
          continue;
          }
#ifdef USE_TERMIOS
        if (c == 27) {
          c = check_special(current->fd);
        }
#endif
        if (c == ctrl('P') || c == SPECIAL_UP) {
          /* Search for the previous (earlier) match */
          if (searchpos > 0) {
            searchpos--;
          }
          skipsame = 1;
        }
        else if (c == ctrl('N') || c == SPECIAL_DOWN) {
          /* Search for the next (later) match */
          if (searchpos < history_len) {
            searchpos++;
          }
          searchdir = 1;
          skipsame = 1;
        }
        else if (c >= ' ') {
          if (rlen >= (int)sizeof(rbuf) + 3) {
            continue;
          }

          n = utf8_getchars(rbuf + rlen, c);
          rlen += n;
          rchars++;
          rbuf[rlen] = 0;

          /* Adding a new char resets the search location */
          searchpos = history_len - 1;
        }
        else {
          /* Exit from incremental search mode */
          break;
        }

        /* Now search through the history for a match */
        for (; searchpos >= 0 && searchpos < history_len; searchpos += searchdir) {
          p = strstr(history[searchpos], rbuf);
          if (p) {
            /* Found a match */
            if (skipsame && strcmp(history[searchpos], current->buf) == 0) {
              /* But it is identical, so skip it */
              continue;
            }
            /* Copy the matching line and set the cursor position */
            set_current(current, history[searchpos]);
            current->pos = utf8_strlen(history[searchpos], p - history[searchpos]);
            break;
          }
        }
        if (!p && n) {
          /* No match, so don't add it */
          rchars--;
          rlen -= n;
          rbuf[rlen] = 0;
        }
        }
      if (c == ctrl('G') || c == ctrl('C')) {
        /* ctrl-g terminates the search with no effect */
        set_current(current, "");
        c = 0;
      }
      else if (c == ctrl('J')) {
        /* ctrl-j terminates the search leaving the buffer in place */
        c = 0;
      }
      /* Go process the char normally */
      refreshLine(current->prompt, current);
      goto process_char;
      }
    break;
    case ctrl('T'):    /* ctrl-t */
      if (current->pos > 0 && current->pos <= current->chars) {
        /* If cursor is at end, transpose the previous two chars */
        int fixer = (current->pos == current->chars);
        c = get_char(current, current->pos - fixer);
        remove_char(current, current->pos - fixer);
        insert_char(current, current->pos - 1, c);
        refreshLine(current->prompt, current);
      }
      break;
    case ctrl('V'):    /* ctrl-v */
      if (has_room(current, 3)) {
        /* Insert the ^V first */
        if (insert_char(current, current->pos, c)) {
          refreshLine(current->prompt, current);
          /* Now wait for the next char. Can insert anything except \0 */
          c = fd_read(current);

          /* Remove the ^V first */
          remove_char(current, current->pos - 1);
          if (c != -1) {
            /* Insert the actual char */
            insert_char(current, current->pos, c);
          }
          refreshLine(current->prompt, current);
        }
      }
      break;
    case ctrl('B'):
    case SPECIAL_LEFT:
      if (current->pos > 0) {
        current->pos--;
        refreshLine(current->prompt, current);
      }
      break;
    case ctrl('F'):
    case SPECIAL_RIGHT:
      if (current->pos < current->chars) {
        current->pos++;
        refreshLine(current->prompt, current);
      }
      break;
    case SPECIAL_PAGE_UP:
      dir = history_len - history_index - 1; /* move to start of history */
      goto history_navigation;
    case SPECIAL_PAGE_DOWN:
      dir = -history_index; /* move to 0 == end of history, i.e. current */
      goto history_navigation;
    case ctrl('P'):
    case SPECIAL_UP:
      dir = 1;
      goto history_navigation;
    case ctrl('N'):
    case SPECIAL_DOWN:
    history_navigation :
      if (history_len > 1) {
        /* Update the current history entry before to
        * overwrite it with tne next one. */
        free(history[history_len - 1 - history_index]);
        history[history_len - 1 - history_index] = strdup(current->buf);
        /* Show the new entry */
        history_index += dir;
        if (history_index < 0) {
          history_index = 0;
          break;
        }
        else if (history_index >= history_len) {
          history_index = history_len - 1;
          break;
        }
        set_current(current, history[history_len - 1 - history_index]);
        refreshLine(current->prompt, current);
      }
                       break;
    case ctrl('A'): /* Ctrl+a, go to the start of the line */
    case SPECIAL_HOME:
      current->pos = 0;
      refreshLine(current->prompt, current);
      break;
    case ctrl('E'): /* ctrl+e, go to the end of the line */
    case SPECIAL_END:
      current->pos = current->chars;
      refreshLine(current->prompt, current);
      break;
    case ctrl('U'): /* Ctrl+u, delete to beginning of line, save deleted chars. */
      if (remove_chars(current, 0, current->pos)) {
        refreshLine(current->prompt, current);
      }
      break;
    case ctrl('K'): /* Ctrl+k, delete from current to end of line, save deleted chars. */
      if (remove_chars(current, current->pos, current->chars - current->pos)) {
        refreshLine(current->prompt, current);
      }
      break;
    case ctrl('Y'): /* Ctrl+y, insert saved chars at current position */
      if (current->capture && insert_chars(current, current->pos, current->capture)) {
        refreshLine(current->prompt, current);
      }
      break;
    case ctrl('L'): /* Ctrl+L, clear screen */
      clearScreen(current);
      /* Force recalc of window size for serial terminals */
      current->cols = 0;
      refreshLine(current->prompt, current);
      break;
    default:
      /* Only tab is allowed without ^V */
      if (c == '\t' || c >= ' ') {
        if (insert_char(current, current->pos, c) == 1) {
          refreshLine(current->prompt, current);
        }
      }
      break;
    }
    }
  return current->len;
    }

int linenoiseColumns(void)
{
  struct current current;
  enableRawMode(&current);
  getWindowSize(&current);
  disableRawMode(&current);
  return current.cols;
}

char *linenoise(const char *prompt)
{
  int count;
  struct current current;
  char buf[LINENOISE_MAX_LINE];

  if (enableRawMode(&current) == -1) {
    printf("%s", prompt);
    fflush(stdout);
    if (fgets(buf, sizeof(buf), stdin) == NULL) {
      return NULL;
    }
    count = strlen(buf);
    if (count && buf[count - 1] == '\n') {
      count--;
      buf[count] = '\0';
    }
  }
  else
  {
    current.buf = buf;
    current.bufmax = sizeof(buf);
    current.len = 0;
    current.chars = 0;
    current.pos = 0;
    current.prompt = prompt;
    current.capture = NULL;

    count = linenoiseEdit(&current);

    disableRawMode(&current);
    printf("\n");

    free(current.capture);
    if (count == -1) {
      return NULL;
    }
  }
  return strdup(buf);
}

/* Using a circular buffer is smarter, but a bit more complex to handle. */
int linenoiseHistoryAdd(const char *line) {
  char *linecopy;

  if (history_max_len == 0) return 0;
  if (history == NULL) {
    history = (char **)malloc(sizeof(char*)*history_max_len);
    if (history == NULL) return 0;
    memset(history, 0, (sizeof(char*)*history_max_len));
  }

  /* do not insert duplicate lines into history */
  if (history_len > 0 && strcmp(line, history[history_len - 1]) == 0) {
    return 0;
  }

  linecopy = strdup(line);
  if (!linecopy) return 0;
  if (history_len == history_max_len) {
    free(history[0]);
    memmove(history, history + 1, sizeof(char*)*(history_max_len - 1));
    history_len--;
  }
  history[history_len] = linecopy;
  history_len++;
  return 1;
}

int linenoiseHistoryGetMaxLen(void) {
  return history_max_len;
}

int linenoiseHistorySetMaxLen(int len) {
  char **newHistory;

  if (len < 1) return 0;
  if (history) {
    int tocopy = history_len;

    newHistory = (char **)malloc(sizeof(char*)*len);
    if (newHistory == NULL) return 0;

    /* If we can't copy everything, free the elements we'll not use. */
    if (len < tocopy) {
      int j;

      for (j = 0; j < tocopy - len; j++) free(history[j]);
      tocopy = len;
    }
    memset(newHistory, 0, sizeof(char*)*len);
    memcpy(newHistory, history + (history_len - tocopy), sizeof(char*)*tocopy);
    free(history);
    history = newHistory;
  }
  history_max_len = len;
  if (history_len > history_max_len)
    history_len = history_max_len;
  return 1;
}

/* Save the history in the specified file. On success 0 is returned
* otherwise -1 is returned. */
int linenoiseHistorySave(const char *filename) {
  FILE *fp = fopen(filename, "w");
  int j;

  if (fp == NULL) return -1;
  for (j = 0; j < history_len; j++) {
    const char *str = history[j];
    /* Need to encode backslash, nl and cr */
    while (*str) {
      if (*str == '\\') {
        fputs("\\\\", fp);
      }
      else if (*str == '\n') {
        fputs("\\n", fp);
      }
      else if (*str == '\r') {
        fputs("\\r", fp);
      }
      else {
        fputc(*str, fp);
      }
      str++;
    }
    fputc('\n', fp);
  }

  fclose(fp);
  return 0;
}

/* Load the history from the specified file. If the file does not exist
* zero is returned and no operation is performed.
*
* If the file exists and the operation succeeded 0 is returned, otherwise
* on error -1 is returned. */
int linenoiseHistoryLoad(const char *filename) {
  FILE *fp = fopen(filename, "r");
  char buf[LINENOISE_MAX_LINE];

  if (fp == NULL) return -1;

  while (fgets(buf, LINENOISE_MAX_LINE, fp) != NULL) {
    char *src, *dest;

    /* Decode backslash escaped values */
    for (src = dest = buf; *src; src++) {
      char ch = *src;

      if (ch == '\\') {
        src++;
        if (*src == 'n') {
          ch = '\n';
        }
        else if (*src == 'r') {
          ch = '\r';
        }
        else {
          ch = *src;
        }
      }
      *dest++ = ch;
    }
    /* Remove trailing newline */
    if (dest != buf && (dest[-1] == '\n' || dest[-1] == '\r')) {
      dest--;
    }
    *dest = 0;

    linenoiseHistoryAdd(buf);
  }
  fclose(fp);
  return 0;
}

/* Provide access to the history buffer.
*
* If 'len' is not NULL, the length is stored in *len.
*/
char **linenoiseHistory(int *len) {
  if (len) {
    *len = history_len;
  }
  return history;
}

}